This invention relates generally to a projectile throwing apparatus and more particularly to a portable, self-contained apparatus for throwing tennis balls and the like.
Apparatus for throwing tennis balls, baseballs, and the like projectiles are employed extensively for training purposes. For example, a tennis ball throwing device can be positioned on a tennis court to automatically propel a tennis ball over the net and thereby simulate actual tennis play. A number of tennis ball throwing devices are presently available on the market. Although such devices perform satisfactorily, they do not provide all of the features which may be desired by the user.
The majority of the presently available throwing devices are not sufficiently portable to be moved from place to place by one individual. Some of those devices must be permanently installed at a particular site, while others, because of their excessive weight, require the use of a dolly to transport them from one site to another.
Another disadvantage of some of the prior known throwing devices is that they require a relatively large source of power. Such a requirement, of course, dictates an increase in the weight of the unit and, therefore, contributes to the nonportability of the device.
Another problem associated with some of the prior known throwing devices is that of providing repetitive, consistent performance. That is, a particular ball throwing device may not be capable of throwing the ball along the same trajectory in successive cycles of operation. Furthermore, many of the presently available throwing devices do not provide the degree of adjustability which is desired for achieving a variety of trajectories or for altering the time period between successive throwing cycles.
One particular tennis ball throwing device which is available on the market employs a ball throwing arm which rotates 360.degree. for each successive throwing cycle. Such a device requires a dwell mechanism to permit the time between successive throws to be within desired and accepted limits. Such a dwell mechanism adds considerably to the cost of the device and generally increases the power requirement thereof.
Another ball throwing device which is presently available on the market employs compressed gasses or air for generating the necessary force required to propel the ball into the desired trajectory. It can be readily appreciated that the use of compressed gas or air is not the most efficient method for imparting a force to a ball. A device which employs compressed gas or air to supply the necessary force to the ball requires the use of a pressurized container which must be periodically recharged. Such containers are relatively heavy, thereby adding to the total weight of the device to reduce its portability. Variation in ball diameters greatly influences the amount of pressure required to release a ball and, therefore, is subject to greater inconsistency.